Histological and ultrastructural investigation of early gonad development and sex differentiation in Adriatic sturgeon (Acipenser naccarii,Acipenseriformes, Chondrostei)

Gonad development and sex differentiation from embryos to 594‐day‐old individuals were investigated in farmed Acipenser naccarii using light and transmission electron microscopy. The migrating primordial germ cells first appear along the dorsal wall of the body cavity in embryos 1.5 days before hatching. The gonadal ridge, containing a few primary primordial germ cells (PGC‐1) surrounded by enveloping cells, appears in 16‐day‐old larvae. At 60 days, the undifferentiated gonad is lamellar and PGC‐1 multiply, producing PGC‐2. In 105‐day‐old juveniles, a distinct germinal area with advanced PGC‐2 appears on the lateral side near the mesogonium and the first blood vessels are visible. At 180 days, putative ovaries with a notched gonadal epithelium and putative testes with a smooth one appear, together with adipose tissue on the distal side. In 210‐day‐old juveniles, active proliferation of germ cells begins in the putative ovaries, whereas putative testes still contain only a few germ cells. The onset of meiosis and reorganization of stromal tissue occurs in ovaries of 292‐day‐old individuals. Ovaries with developed lamellae enclosing early oocyte clusters and follicles with perinucleolar oocytes occur at 594 days. Meiotic stages are never found, even in anastomozing tubular testes of 594‐day‐old individuals. Steroid producing cells are detected in the undifferentiated gonad and in the differentiated ones of both sexes. Anatomical differentiation of the gonad precedes cytological differentiation and female differentiation largely precedes that of the male. Gonad development and differentiation are also associated with structural changes of connective tissue, viz. collagen‐rich areas are massive in developing testes and reduced in ovaries. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

Comparison of myeloproliferative sarcoma virus with Moloney murine sarcoma virus variants by nucleotide sequencing and heteroduplex analysis.

The myeloproliferative sarcoma virus (MPSV) was derived by passage of Moloney sarcoma virus (Mo-MuSV) in adult mice. Mo-MuSV variants transform fibroblasts. However, MPSV also affects erythroid, myeloid, and hematopoietic stem cells. The MPSV proviral genome, two temperature-sensitive mutants derived from it, Mo-MuSV variant M1, and Moloney murine leukemia virus (Mo-MuLV) were compared by heteroduplex mapping. MPSV wild type was found to have 1 kilobase pair deleted from the pol gene and to contain v-mos-related sequences. The 3' end of MPSV, including the oncogene-helper junctions, the v-mos gene, and the 3' long terminal repeat, was sequenced and compared with sequences of Mo-MuLV, MSV-124, and the mouse oncogene c-mos. From these data, MPSV appears to be either closely related to the original Mo-MuSV or an independent recombinant of Mo-MuLV and c-mos. Five possible explanations of the altered specificity of MPSV are considered. (i) The MPSV mos protein has properties inherent in c-mos but lost by other Mo-MuSV mos proteins. (ii) The MPSV mos protein has altered characteristics due to amino acid changes. (iii) Due to a frameshift, MPSV codes for a mos protein truncated at the amino terminal and also a novel peptide. (iv) A second novel peptide may be encoded from the 3' env region. (v) MPSV has long terminal repeats and an enhancer sequence more like Mo-MuLV than Mo-MuSV, with a consequently altered target cell specificity.     

Patterns of protein synthesis at the onset of oogenesis in the mouse

Two-dimensional electrophoresis has been used to examine the pattern of proteins synthesized in germ cells at the beginning of oogenesis in the mouse. Three stage-specific changes in proteins were detected during the three observational periods studied (12, 14, and 17 days of gestation). One protein is present in 12 day female germ cells and nongerminal gonadal preparations, but disappears by day 14. Two of the proteins appear for the first time in fourteen day female germ cell preparations, and are not detectable in nongerminal gonadal tissue. No stage-specific changes in proteins were observed in preparations of male germ cells of the same age. A preliminary DNA-binding protein analysis suggests that none of the stage-specific proteins mentioned above are DNA-binding proteins.     

Patterns of Protein Synthesis at the Onset of Oogenesis in the Mouse

Two-dimensional electrophoresis has been used to examine the pattern of proteins synthesized in germ cells at the beginning of oogenesis in the mouse. Three stage-specific changes in proteins were detected during the three observational periods studied (12,14, and 17 days of gestation). One protein is present in 12 day female germ cells and nongerminal gonadal preparations, but disappears by day 14. Two of the proteins appear for the first time in fourteen day female germ cell preparations, and are not detectable in nongerminal gonadal tissue. No stage-specific changes in proteins were observed in preparations of male germ cells of the same age. A preliminary DNA-binding protein analysis suggests that none of the stage-specific proteins mentioned above are DNA-binding proteins.     

Oocyte formation by mitotically active germ cells purified from ovaries of reproductive-age women

Germline stem cells that produce oocytes in vitro and fertilization-competent eggs in vivo have been identified in and isolated from adult mouse ovaries. Here we describe and validate a fluorescence-activated cell sorting-based protocol that can be used with adult mouse ovaries and human ovarian cortical tissue to purify rare mitotically active cells that have a gene expression profile that is consistent with primitive germ cells. Once established in vitro, these cells can be expanded for months and can spontaneously generate 35- to 50-μm oocytes, as determined by morphology, gene expression and haploid (1n) status. Injection of the human germline cells, engineered to stably express GFP, into human ovarian cortical biopsies leads to formation of follicles containing GFP-positive oocytes 1-2 weeks after xenotransplantation into immunodeficient female mice. Thus, ovaries of reproductive-age women, similar to adult mice, possess rare mitotically active germ cells that can be propagated in vitro as well as generate oocytes in vitro and in vivo.     

An ovarian regression syndrome in the platyfish, Xiphophorus maculatus

The highly inbred Coatzacoalcos (Cp) strain of the platyfish, Xiphophorus maculatus, was noted for a high percentage of infertile females (XX). The ovaries of approximately one-quarter of all females regress. The time of gonadal atrophy varied from before sexual maturation up to 11 months of age. The gonadotropic zone of the pituitary was hypertrophied in regressed females. Transplants of immature testes and ovarian tissue into the caudal musculature of regressed females and the subsequent maturation of the grafts demonstrated that the ovarian degeneration was not due to pituitary or hypothalamic malfunction or an autoimmune disease. The cause of the gonadal degeneration was apparently localized to the ovary itself. This phenomenon was never observed in males (XY). Regressed ovaries fell into two categories, designated types I and II, with all being characterized by the presence of ductlike structures which resembled male efferent ducts, lined by Sertoli cells. Type I ovaries bore a marked similarity to certain mammalian dysgenetic gonads, while type II ovaries contained many proliferating germ cells and could be compared to the human neoplasm termed gonadoblastoma. It is suggested that the physiological lesion responsible for the ovarian regression syndrome involves the processes that control the determination and differentiation of the germ cells similar to those found in human 46,XY gonadal dysgenesis.